Sound head for reproducing sound from sound films



Nov. 24, 1936. D. P. FISHER 2,062,217

SOUND HEAD FOR REPRODUCING SOUND FROM SOUND FILMS Filed July 26, 1934 2 Sheets-Sheet l Nov. 24,1936. D. P. FISHER SOUND HEAD FOR REPRODUCING SOUND FROM SOUND FILMS Filed July 26, 1954 2 Sheets-Sheet 2 Patented Nov. 24, I936 UNITED STATES PATENT OFFICE SOUND HEAD FOR REPRODUCING SOUND FROM SOUND FILMS David Percival Fisher, Wellington, New Zealand Claims.

This invention relates to cinematograph and sound projecting machines, and particularly to that portion of the machine for reproducing the sound from a sound film.

, 5.. The chief object of the invention is to obviate or: reduce the fluctuation of the film during its passage through the sound gate.

According to my invention, I provide a fly .wheel drum on which the film runs after it .10 leaves the intermittent sprocket of the projector, and also a roller having means to prevent sudden variations of-speed thereof, such roller placed at a position just before the entrance of the light aperture, usually termed the sound gate.. This arrangement provides (1) that the flutter or vibration of the film as it leaves the .intermittent sprocket will be damped or arrested as the film passes over the fiy wheel drum, and (2) that the film will be prevented from sudden variations of speed as it passes through the sound gate by means of the roller referred to.

I provide also a device consisting of a pulley mounted by means of a spring upon a weighted v The invention will be described with the aid of the accompanying drawings, wherein: Figure 1 is an elevation of the invention. Figure 2 is a plan. Figure 3 is an end view. Figure 4 is a. front elevation of the pulley device, and

Figure 5 is a side elevation thereof.

40 Figure 6 is a diagram showing the operation of the pulley device.

Figure '7 is an obverse view of the drum showing how it is mounted, but drawn to a larger scale.

5 Figure 8 is a cross sectional elevation on line A-A Figure '7.

Referring to the drawings, the apparatus consists of the usual parts of a sound head, namely casing or frame I, photo-cell 3, optical sys- 5 tem 4, sound gate 5, take-up sprocket 6, and

guide roller 1, the film 8 leading from the intermittent sprocket 9 of the projector apparatus.

In this invention, a steadying roller 2 with or without sprocket teeth, the one illustrated 55 having sprocket teeth, is placed at a position close to the leading-in side of the sound gate 5, and has a fiy wheel ll upon its spindle for the purpose of preventing any sudden variation in the speed of the sprocket. The usual practice is to place a sprocket below the sound gate, in 5 which case it must be driven by other means than the film. In this invention, the sprocket 2 is not in any way equivalent to a sprocket placed on the leading-out side of the sound gate. The sprocket 2 is not for the purpose of draw- 10 ing the film but to enable the fly wheel to be rotated for steadying the speed of the sprocket, so that a smooth roller in place of a sprocketed roller may be. preferable in some cases.

At a suitable position from the intermittent 5 sprocket 9, so as to form a loop A in the film, there is placed a heavy fly wheel drum 10 which is adjustably mounted, as will hereinafter be described, and over which the film 8 passes. It

has a recessed portion in the centre so that the O centre of the film does not contact with the drum. The film is given the required peripheral contact with the drum by a roller I9 mounted, as will be hereinafter explained. By so positioning the drum H), the flutter tending to occur 25 in the film 8 after it leaves the intermittent sprocket 9, will be clamped by reason of the heavy fly wheel drum [0, and the film will then pass in a fairly steady condition to the sprocket 2, which will complete the steadying effect, so that the film will be completely steady as it passes through the sound gate. The film, after it leaves the sound gate 5, passes over the guide roller 1 and thence over a pulley I 2 which is mounted by means of a spring l3 upon a weighted pendulum M pivoted on a pin l5 fixed in the frame I so as to be free to swing or oscillate according to variations of the pull due to varying speeds or inaccuracies of the take-up sprocket.

The pulley I2 consists of two independent pulleys spaced apart so that the edge of the film will be carried by them (see Figures 3, 4 and 5).

It will be seen, therefore, that by disposition of the sprocket 2 and fly wheel drum I0, the film would lead from the usual intermittent projector sprocket 9, over the fiy wheel drum [0, and over the sprocket 2 against which it is retained by a suitable guide pulley I! and thence through the sound gate to and around the guide roller 1 and thence over the spring mounted pulley I 2, and thence to the take-up sprocket 6.

Should any variation of speed in the film take place between the sprocket 2 and the take-up sprocket 6, it is immediately corrected by means of the pulley l2, for example, if the portion of pulley I2 moving back to the position shown in full lines in Figure 6.

The fiy wheel drum I is rotatably mounted on a pin 20 fixed in an arm 2| through which a pin 22 is screwed into the casing l" and secures the arm in a selected position. The roller 19 is pivoted freely on aspindle 23 projecting from an arm 24 fixed on a pin 25 entering a boss 26 of an arm 21 pivoted on a boss 28 of .the arm The pin 25 is reduced and has a coil spring 25 around it and attached at one end to thepin 25 and its other end attached to a cap '30 fitting within the boss 26 and secured on the pin by a screw 3L. Thecap 30 can, therefore, rotate on the .pin 25, and .the tension of the spring can thusbe adjusted, thelcap 30 being secured by a set screw 32. Thus, the requireditension can be given tothe roller. l9. The arm 21 can also be adjusted .ontheboss 28 of the arm 2! and secured thereon by a set pin 33 passing through the end of the arm which is in the formof a split boss.

' placed closer or further from the intermittent sprocket 9 so as to obtain the. best position in each case. The alternating ofithe position of the drum would cause the roller I9 to lie either nearer the top of .the drum onmore towards the lower hpartthere'of, but by slackening the screw 33 the arm can be rotated on the bossx28. andthe roller .ilel thereby adjusted to .the best position in relation to thexdrum.

.after it has passed through a sound gate, consisting of a pulley, a spring on the upper end of l which said pulley is rotatably mounted, a pendu- .lum weight pivoted on an axis parallelwith that ot the pulley. so as to swing from such axis, said spring having its lower end attached to said pen dulum weight.

27 Means for regulating the motion of a film in passing through a sound gate, in combination, a sprocketed roller over which the film passes, said sprocket roller driven by the film and located immediately before the entrance of the sound gate, inertia means on the spindle of said sprocket roller, a guide pulley over which the film passes supported beyond the sound gate, a

l spring pulley, a weighted pendulum on which said pulley is mounted in order to prevent variations inthe film beyond the sound gate afiecting that portion of the film between the sprocket roller and the guidelpulley.

3. In the device as claimed in claim 2, said springw uide pulley having a spring secured to l the pendulum and carrying at its upper end the said pulley.

4. In a cinematograph and sound projecting machines in which the film after. it leaves the in- Ltermittent sprocket lof the '5 projector npasses through a. sound gate, aframe, a fiyewheel .drum

for dampening irregular motion inithetfilm an .arm' adjustably attached to i said frame .Jandg. meansfor holding said armin adjustedaposition,

said fiyl-wheel' drum being lmountedlonvsaid arm, and means for holding :thefilm inflcontactewith the periphery of the spring drumlcomprising, a

secondarmpivotally mounted 011113118 axleofisaid; .fiyewheel drum, means for. .holding..-sa.id;;second arm in adjustedposition, and a third-annpivoted .onosaid second. arm, alroller mounted .in said third arm and: spring :means. for, pressing said third arm into contact with the. iperipheryfof; said; .fly-wheel drum.

'1 ;sIn. ,dampening means for removinglflucwatingand irregular. motion inv alfilmi'on itsxpath to thecsound gate, a frame,,an arm adjustably attached to .saideframe, means for holding-xsaid arm in. an adjustedaposition, and la l cylindrical self-contained flywheel drum freely mountedon ".said a-rmtoirotate on'its own axis, saidwdrum of large diameter to provide. a large circumferential during its rotation andxmeans ,for' pressing; :the filmwagainst the periphery of the drum to give suflicientlengthof contact and friction between thefilm and the drum to rotate said drum.

' l DAVID; P; FISHER. 

